To get chapters starting on new pages/screens you need a new-page command, which you specify in a style section in the HTML you feed to Librarian. Lots of stuff goes there.
Some notes here, with the style line you want being something like
.pg {page-break-before: always}
used something like
<div class="pg" style="text-align: center">
<h2>Two: A Dash of Pepper</h2>
</div><br /><br />
which will start that chapter at the top of the next screen.
There are a bunch of commands you can use if you want to put in the time to make the output pretty.